valiantwagonguy
Well-Known Member
Go to work,work overtime a few hours , buy a new set of bearings , and throw this one in the trash.Write it off as the cost of your engine building education and move forward
Brand new main bearing nicked. Usable?
- Thread starter JoePole1
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dartfreak75
Restore it, Dont part it!
Rock auto! Enginetech bearings set is 21 bucks.
dartfreak75
Restore it, Dont part it!
Or imo just use this one it looks fine check your tolerance with plastigage if it it's good run it!
Well that sucks, I wasnt expecting them to "warranty" it but hell you should be able to buy a single if need be. Pi$$ poor customer service if I'm reading right lol.
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MopaR&D
Nerd Member
I'd run it just because I can't think of what would go wrong having a small nick out of the side like that, maybe if it was down in the center I'd be more concerned but that'll basically just act like a small oil reservoir if anything. Although I personally haven't messed with enough old engines to see a bad main bearing with my own eyes. Rod bearings, heck yeah those get destroyed all the time.
I could be worried I didn't get the last 7 or so visible dust particles out of my valley before putting the intake on but you gotta draw the line somewhere lol.
I could be worried I didn't get the last 7 or so visible dust particles out of my valley before putting the intake on but you gotta draw the line somewhere lol.
dartfreak75
Restore it, Dont part it!
I agree if it where me is run the original one he pictured as long as it passed tolerance testing
In my opinion, I'd scrap ALL of those King bearings and get a set of Clevite or Federal tri metal bearings if possible. That little pit in that bi metal bearing isn't going to hurt anything if your hard pressed and have to use them, I just ain't impressed with those cheaper King bearings. They make a more expensive line of bearings,but I don't have any experience with those. Ran them in a 360 rebuild and in a couple Chevy circle track motors. Nothing but trouble. Replaced them with tri metal bearings and ran the **** outta them for years. Good luck with whatever you end up doing. Just my 2 cents bud
MopaR&D
Nerd Member
If the bearing quality is questionable like you say then I take back my comment, change them out for good ones I've used Clevite 77 bearings with good results. Come to think of it even factory bearings are tri-metal...? They definitely have a copper layer underneath the top layer, then steel.
famous bob
mopar misfit
^^^^^^^^^^^^^^^^^^
Never use any "grit ' on a bearing , scrape the hi spots carefully, barely touch w/ fine scotch brite if u want.
I know a guy that scotch brites bearings occasionally to get about a 1/4 of a thousanth on each half , never has one come apart that I know of.
famous bob
mopar misfit
Much less # 5 !! It and the thrust bearing are likely the most loaded !-
MopaR&D
Nerd Member
I thought the center 3 main caps were the most loaded, that's why they're always the ones with cross-bolts or extra splayed bolts? And thrust loading is totally separate from radial loading with much lower forces unless you're dumping the clutch doing holeshots in a stick-shift car. IIRC the momentum of a piston/rod assembly at 5000 RPM is on the order of several tons of pressure pushing on the rod journal back-and-forth hundreds of times a second.
The load is not back and forth. It goes all of the way around the bearing. Think of a marble in a can and whirling it around.
The load is not back and forth. It goes all of the way around the bearing. Think of a marble in a can and whirling it around.
nm9stheham
Well-Known Member
I suspect that is due to the block and webs being the least supported, and thus the weakest and subject to the most flexing, at 2, 3, and 4.
Bearings are not evenly loaded all around. The bottom area is the most loaded as it takes the peak force of the combustion process, which can be well above 10,000 lbs peak on each rod with any significant HP. Check it out here in the Clevite-Mahle performance catalog; look at page 19, which leads into interesting info on why full grooved bearings are not always the best for the mains. (It is a trade-off versus better rod oiling.)
https://www.mahle-aftermarket.com/m...s-and-literature/engine-bearings/eb-40-16.pdf
Replace that? Seriously? I would have hit that with some fine scotchbrite or some 00 steel wool and never slowed down.
Duane
Well-Known Member
I would run that.
Duane
Well-Known Member
Tell that to the Chrysler engineers who still recommend a full groove main bearing for a performance application to adequately oil the rods. Although I have noticed on modern clevite "H" series bearings that the oil groove is not nearly as wide as it was in years past.
To my knowledge at the time of assembly Mahle did not offer a full grooved main bearing set for the sbm.
But I noticed later that Mopar performance was selling "H" series bearings fully grooved with the narrow #5 main. They must have had them made by clevite. So Chrysler still believes in fully grooved mains.
True. Have a look at my used bearings in post 5. The upper looks near new.
This mill had 70k and it was in a Ram 2500. It also had a bent #8 rod to boot.
famous bob
mopar misfit
The center 3 mains are the weakest, due to not being incorporated in the front and rear block walls , and the bottom shells do receive the most ponding.
If u think there is no stress on # 3 thrust bearing in a hemi or big block, why do they go south occasionally in hi h.p. , hooked up drag cars?
It was enough of a problem that the Chrysler drag seminars had some teaching on them back in the day . Most teams back then changed bearings on the prostock type cars regularly.
I lost a thrust bearing in a hemi s/s car once and learned of the problem from Tom Hoover.
Of course a lot if u younger guys probly don't even know who he was.
He was called the god father of the hemi.
Things have come a long way since then tho in engine and bearing design , I guess-----------
nm9stheham
Well-Known Member
Your 1st sentence is the key..... 'for a performance application'. For a lo-po, d-driver, or cruiser use, where the rod oiling is adequate as-is, no need for full groove, and it may lead to accelerated main wear at the lower oil pressures (idling, daily driving around town). That is the reason that I said it is a trade-off, and I would encourage folks to understand why to go one way or the other.
Now here is an interesting compromise at least for 360's: 3/4 groove.... never knew that existed.
What main bearings for a high performance engine?
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Duane
Well-Known Member
Agreed.
Yes I believe federal mogul makes a 3/4 groove for the sbm.
Part of the point I was trying to make was even if you told Mahle clevite you were building a bracket drag motor (which I did) they will still try to convince you to go with a 1/2 groove bearing.
There is not a consensus on full grooved.
But yes for a regular engine I agree they are not necessary.
nm9stheham
Well-Known Member
Yep, from their documents, they believe it is the way to go. I've found test and research articles supporting the use of a full lower, and it is actually more justified the more the engine is powered up.
BUT, like so many things in this world, it all has to be conditioned on other factors specific to the engine.... the limits in oiling the SBM rods at high RPM are a known thing. Where that 'high RPM' range starts, I really can't say.
Bret Tschacher
Well-Known Member
Nicks in bearings are not what is the problem, it's when there is a nick in the crank that you can feel rising above the rest of the journal !!! I never saw any pics of what this post is about, however, in over 40 years of building engines from Briggs and Stratons to big Catapillars and whatever is in the between,, Fords, Chevys AMC's, Hondas, Toyota's and racing Mopar big and small blocks I have see about everything that could be seen including some amature reassemble his Big Block Chevy for his power boat and installing the pistons in the wrong banks thereby getting the rod offset against the radius fillet which resulted in a trashed set of well everything in the end. I saw one 440 that someone the pistons backwards with open chamber heads and used 2 head gaskets under both heads to get the motor to turn over even. They were a set of TRW low domed pistons. I guess the guy was trying to get more compression and get the flame front under control like a set of closed chamber early heads would have done. I don't believe that engine ever ran as I got it in a boat that had a starter from an old 392 fire power with the 440 flex plate, the drive teeth did not match and it was terrible sounding. The Chevy bearings simply failed very fast polluting the engine to the point of metal getting past the pressure relief valve at the oil filter and taking out the cam bearings and the mains. Any how, I will address the issue of to Full Groove or to not full Groove that is the question! Never go with Full Groove when there is always an option. Full Groove bearings will reduce the load capacity on ANY engine which the crank must carry! There are a few listings for Chevy engines with 270 degree/ 3/4 groove lower half inserts. These will give you the best of each benefit, better oiling without loosing bearing surface to support the main. After sufficient time running, if you dismantle an engine that has been full groove, and measure the crank, you may even be able to see the ridge that will develop on the main journal from lack of support where the groove is ! There has always been the practice of cross drilling the mains which Oldsmobile did from many years on most of their engines. This is a blessing and a curse as it weakens the crank but with forged cranks it is not as big an issue as full grooved mains. The old Newtons law of an object in motion tends to stay in motion applies here as well. Fluids are object, and if moving one way will stay moving the same way. Yes even under pressure ! I know someone is going to contest this but that's fine. Go ask a physics professor or an engineer. The guys on engine masters will tell you. I haven't seen a part # listed for 3/4 bearings for any of the Mopar lately. But I did build an engine years ago, a 318, and I had tooling in shop that allowed me to manually machine additional grooves into the lower insert giving me a set of 3/4 bearings for that engine. I was very diligent with my work and I ran that engine for several years, raced it, drove it from western Neb. in the early 80's to the south valley region of Calif. and drove it and raced it there for a fair time, not too many races lost with that one, was called a liar more than once. Some people swore it was a 340 that I had altered the stampings on the block. Anyway, Scotch briting bearings is common, I would guess a many engines have been put together with a nick in a bearing that never caused any problems. I have seen engines taken apart by me and others that the bearings looked horrible. They were still running and still had oil pressure. Hell I know a guy in Bakersfield that had a piece of a valve stem seal get into the pump in his small block Ford and twist the oil drive shaft off loosing complete lube and he drove that car several miles to get it home with the lifters clattering. He made it and we pulled the pan, bearings, all of them, and miced the crank, it was undamaged, the bearings looked like hell but I put in a new of bearing, put it all back together and we drove and rode around for a couple of months with no problems. He build another engine eventually to replace the 289, a 302 with more performance additions. So Bearings are bearings, they can have take a lot more than what you would think.
Bret Tschacher
Well-Known Member
Take a look that the firing order and you will see that the center main takes 4 consecutive hits in one revolution from ,3,4,5,6 cylinders, that is the reason Ford changed the firing order in 302, 351 and in the end changed the later year 302 to the same as the 351 windsor. As far as incorperating the center mains into the block ? Look again ! What would you call the webbing between the bolts and the pan rail ? Most all V8 engines suffered from the same problems this post is about. That is why Chevy changed from the small block to the LS order, why cam grinders offer a 4-7 swap cam for many engine, why Ford has a different order on nearly all of their engines. There are cams that go beyond the 4-7 swap with 2 more cylinders but that simply moves the load from the center main to the 2 and 4 main. Better that I suppose since you now have load sent to all 5 mains, the rear, not much to do about that one with a heavy fluid filed convertor or heavy flywheel, and the front, a belt with tension on it all the time and a chain to run the cam or cams with tensioners on them as with the Tritons and a couple of others.
Bret Tschacher
Well-Known Member
The limit starts with the viscosity of the oil and the temperature of it. It also calls into issue the diameter of the journal as in with big block Fords, a massive bearing will fail very soon at high rpms because oil no matter how thin or thick, the oil can only travel to a certain speed, beyond that is sheer point which is where the bearing overheats and fails. The same factor affects pistons and cylinder walls. There are formulas and even charts that give limits so you can calculate all of these factors when you are bench racing. Strokes , rod lengths, bore offsets, pin offsets, all kinds of things to work with here. Journal sizes, clearances affect it too. Look at an Indy engine, with a tiny main journal and rod journal with a really short stroke and a bore that is massive when it come to bore to stroke ratio. You would wonder how it even stays together with such large side clearances and things like piston guided connecting rods. Those engine run such tight oil clearances they have to preheat the engine and oil before they will even turn over to start without trashing the bottom end. Going back to the SBM engine there are so very few old 340's and even the other engines left around the were run as race engine simply because the front main split all the way up to the cam because of the oil passages drilled there. not just one but three. Too much casting was taken out for necessary lubrication, which could have and should have been done differently in this design with relocated feeds like in the center or rear of the block. GM went through this with their Gen IV, V, VI and then the VII's winding up with what they cal priority mains oiling system. The only thing I found with these in the later years is the size of the holes was reduced to the point that in many engine blocks like the later 454 and medium duty tall deck 427's the factory actually had miscalibrated drilling processes in the factory and the intersections from the main oil gallery to the passages to the mains missed and the engines had mulitple crank and bearing failures !!! I recently completed a rebuild of one engine that suffered from this where another shop, make that the first shop that attempted to repair this engine and even a machine shop that did and redid this engine and failed to find this problem. At various time with this engine full groove mains were installed which aggrevated the problem, a high volume high pressure pump was tried and even an oil cooler delete was tried, the only fix was to re drill the oil feeds. Bottom line when building an engine for anything beyond what the factory did, such as what most of us do, is to check EVERYTHING, oil passages, clearaces and as I said in other post, I will never go with another set of Full Grooves, I had cross drilled cranks, modified half groove bearings, I have even drilled out the holes in the upper main inserts to match the hole I drilled in the blocks to insure that more oil CAN get to the Mains and Rods. NO engine ever made at a factory isn't capable of giving more then what the factory gives you if you pay it to do so! The only limit is how much can the block and other parts take before something starts to say that is all like splitting or just blowing up like when a rod bolt fails, which in more case than not is a result of lack of oil to it.
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